Die head



May 27, 1930. H; T. SHEARER DIE HEAD Fild Nov. 5, 1925 '7 Sheets-SheetDIE HEAD '7 Sheets-Sheet 2 Harry Tshearer H. T. SHEARER Filed Nov. 5,1925 May 27, 1930;

M EH m 4 mm w Z3 May 27, 1930. I L-T; SHEARER.

DIE HEAD Filed Nov. 5, 1925 7 Sheets-Sheet 3 QH'UWH Har y TS/zearer May27, 1930.- H. T. SHEARER DIE HEAD Filed Nov. 5, 1925 7 Sheets-Sheet 4'gwuemtov Harry T511987?! H. T. SHEARER May 27', 1930.

DYIE HEAD Filed Nov. 5. 1925 '7 Sheets-Sheet 5 Zlwuawtoz Harm TshearerH. T. SHEARER DIE HEAD Filed Nov. 5, 1925 '7 Sheets-Sheet 6 gvvuwntozHarry T s/768F491" May 27:, 1930; H. T. SHEARER DIE HEAD- I Filed Nov.5. 1925 '7 Sheets-Shee t 7 grwcwtoz I Evrry TS/veamr Patented May 27,1930 UNITED .STATES PATENT OFFICE HARRY '1. SI-IEARER, OF WAYNESBORO,PENNSYLVANIA, ASSIGNOR TO LANDIS MA- CHINE COMPANY, OF WAYNESBORO,PENNSYLVANIA, A CORPORATION OF PENNSYL VANIA.

DIE HEAD Application filed November My said invention relates to a diehead for machines such as are used for cutting thread on bolts, pipes,etc., and as here shown is embodied in a non-rotary thread-cutting 5device of the type known'as the Landmatic die head. In the use of headsof this type the head ordinarily travels toward the work but isnon-rotary while the work rotates and the opening of the head is usuallyeffected by 1 retardingthe axial movement of the member carrying thehead. The improved head here disclosed has distinct advantages overthose previously known in economy of manufacture, economical operationof the head and improved character of output. It is to be understoodthat the application of the various features of the invention, however,is not limited to the specific type of machine shown in the drawings assome of the features may be applied to the head, etc.

The primary object of my invention is to provide a die head of thischaracter in two units divided approximately along a plane perpendicularto the axis of the head. Such 5 a construction affords very importantadvantages over previously known devices. One advantage resides in thefact that it fa cilitates assembling and disassembling parts of the headwhich in ordinary constructions are operations of very considerabledifficulty and which ordinarily are decidedly timeconsuming.

Another advantage resides in the possibility of accurate adjustment ofthe endwise float of the trunnions on which the chaser holders aremounted. These chaser holders and trunnions oscillate and therefore acertain amount of clearance is necessary between the end faces of saidparts and the parts abutting against them, this making for a certainvery limited endwise movement or float between the relativelyoscillatory parts which compensates for certain slight inaccuraciesoccurring in devices of this character. It is essential to the bestoperation of a thread cutting die head that this float be very limitedin extent and precisely the same in different trunnions located inspaced relation about the opening in the head so as to form the threadsaccurately and precisely 5, 1925. Serial No. 67,136.

on the work and-my invention provides convenient positive and accuratemeans for securing this result. It is vital also in order to secure goodwork thatabsolut'e parallelism shall exist between the contacting endfaces of the head body, the rings surrounding it and the rear faces ofthe chaser holders. The two unit head here described makes this moreeasy to secure and maintain than with the usual constructions heretoforeknown.

Another object of the invention is the elimination of screws,screw-slots and other features providing dirt pockets on the face of thehead, such as are detrimental to successful and economical operation ofthe same.

Another object is to provide spring means for opening the head whichmeans does not act directly on the chaser holders and so does not affectthe float of the chaser holders.

Another object is to provide improved means for rotatably adjusting thehead body relativelyto the other parts of the head to vary the size ofthe opening between the chasers when the head is closed.

Another object of my invention is to provide an improved tripping orhead opening mechanism for use in a head having locking pins with bluntends which are completely withdrawn from the closing ring to permit.

the head to open.

Referring to the accompanying drawings which are made a part hereof andon which similar reference characters indicate similar parts,

Figure 1 is a side elevation of my improved die head with one chaserholder in position thereon,

Figure 2, a face view of the head with three chaser holders removed,

Figure 3, a longitudinal section of the front unit of the head,

Figure 4, a rear view of the front unit, Figure 2 serving as a faceviewthereof,

Figure 5, a section on line 55 of Figure 2, Figure 6, a section on line6-6 of Figure 1, Figure 7, a detail of a part shown in F igure 6,

Figure 8, a section ofthe rear unit of the head, this view being sopositioned with reference to Figure 3 as to indicate the position ofsaid units when about to be assembled,

Figure 9, a face View of the rear unit of the head,

Figure 10, a longitudinal section of the as sembled head with the partsin closed position,

Figure 11, a detail section showing the relative positions of certainparts when the head is open,

Figure 12, a front elevation of said parts, partly in section,

Figure 13, an elevation of a locking pin, such as is illustrated inFigures 8, 11 and 12,

Figure, 14, a fragmentary section of a closing ring locked in the closedposition of the head by pins of the type shown in Figure 13,

Figure 15, an elevation of a modified locking pin,

Figure 16, a face view of a closing ring locked in the closed positionof the head by pins of the type shown in Figure 15,

Figure 17, an elevation of a modified lockmg pin,

Figures 18 and 19, fragmentary cross sections of a closing ring lockedin different operative positions by a pin such as shown in Figure 17,

Figure 20, a face view of a front unit employing a closing ring ofmodified character,

Figure 21, a fragmentary elevation, partly in section, of the device ofFig. 20,

Figure 22, a section on line 22-22 of Fig. 21,

Figure 23, a longitudinal section of a head of the character abovereferred to, equipped with internal tripping mechanism,

Figure 24, a face view of an internal tripping element,

Figure 25, a face view of a modified chaser holder,

Figure 26, a bottom plan of Figure 25,

Figure 27, a longitudinal section of the chaser holder as shown inFigures 1 and 2 excepting that in Figure 27 the trunnion is integralwith the chaser-holder,

Figure 28, an end view of the clamp of the chaser holder as shown inFigures 1, 2 and 27,

Figure 29, a fragmentary end elevation of a chaser holder as shown inFigures 25 and 26,

Figure 30, an end View of the chaser used in the chaser-holder in Figs.25, 26 and 29,

Figure 31, an end view of the chaser shown in Figures 1, 2 and 27, and

Figure 32, an end view of the clamp used in Figures 25, 26 and 29.

The head comprises a front unit and a rear unit which are readilyseparable from each other, but in operation are held together by meanshereinafter described.

dicates the head body member, which is carried by the assembled frontunit. A ring 31 encircles the head body, forward movement of the ringbeing prevented by an encircling flange 32 engaging in an annular groovein the ring. Behind the ring 31 there is an adjusting ring 33 and beyondthis a zero plate 34 having a rearwardly projecting flange 35 bearingzero marks (Fig. 1). The plate is necessarily formed as a ring and has arela tively small central opening surrounding a reduced rearwardextension 36 on the head body. The plate is secured to the head body bymeans of screws 37. .A pin 38 serves to position the ring relatively tothe head body and-for this purpose a series of four holes is providedfor engagement by said pin which holes are spaced 90 from each other.

The head body has a longitudinal central opening and a number ofbearings parallel thereto in which are journalcd trunnions 39. At theirrear ends these trunnions have reduced threaded extensions passingthrough openings in the ring 34. Nuts 40 threaded on said extensionshave flanges 41 bearing against the ring 34. Locking screws 42 (Fig.'10) have threaded engagement in the nuts 40 and are tapered at theirforward ends for engagement with tapered recesses in the ends of thetrunnions 39. The nuts 40 may readily be adjusted to provide thenecessary float for trunnions 39 between flanges 41 of nuts 40, the ring34, the faces of holders 43 and the faces of ring 31 and head body 30.After the adjustment is made the locking screw 42 is caused to engagethe end of the trunnion with sufficient friction to guard againstaccidental release. It will be seen that the construction of the headwith parallel bores and flat end faces makes a very simple job ofmachining since the bores can be machined straight through so that onlystraight bores and flat faces need be machined. It is thus acomparatively simple matter to form the contacting faces of the rings,the head, the trunnions and their adjusting nuts very accuratelyparallel so as to make the parts work easily and reduce to a minimum theerror arising from non-parallel parts. By this construction the float ofthe trunnions may be Very readily and accurately adjusted, with uniformfloat, all of which is essential for precision work. The machining ofthe outer and rear faces of the encircling flange 32 so that it will fitin the groove of the closing ring 31 also becomes a relatively simplematter. No depressions are required for screws, nor will there be anyprojecting screw-heads to interfere with the movement of thechaser-holders, and the possibility of cracks or openings in the face ofthe head wide enough to admit dirt is reduced to a minimum.

At the forward ends of the trunnions there are chaser-holders 43 fixedto the trunnions for oscillation therewith. The chaser holders areconnected to the closing ring 31 by means of pivot pins 44 carryingblocks 45 slidably mounted in slots in the chaser holders. In thepresent embodiment of the invention the chaserholders are attached tothe trunnion by means of screws 46 though in some instances they aremade integral therewith.

The rin 33 is provided with one or more openings tting closely aboutpins 47 on the rear unit. These pins engage at their forward ends inopenings in the closing ring thus holding the chasers in operativeposition for acting on the work. These openings are provided withhardened bushings 48. The purpose of the bushings is to prevent theholes from wearing large at the-entrance which would interfere withquick and accurate entry of the pins 47. It will be seen that when theclosing ring moves to bring the bushings out of registry with the pinsthe pins will bear against the ends of the bushings as clearly shown inFigure 12. Ring 34 is provided with clearance openings (Fig. 4) for pins47 and for screws 49 by means of which the. front and rear units areheld together. I

A pin 50 is fixed in the ring 31, this ring being flattened at oppositesides to provide abutments against either of which a spring 51 may bear.The spring 51'is positioned in a passage in the ring 33 said passagebeing nearly tangential to the head body and intersecting a chamber at52 which is open at one side for entry of the pin 50. The spring is heldin place by a cap 53 having a hollow end in which the spring is seated.The cap has threaded engagement with such passa e and its movement islimited by a shoulder engagin a shoulder on the ring 33. The other end 0the passage is closed by a threaded plug 54 having a head resting onanother shoulder on the ring 33. Assuming the parts to be in positionfor cutting a righthand thread it will be seen that when the lockingpins 47 are withdrawn the closing ring will be released and the spring51 will force it in a direction to render the chasers inoperative. Ahandle 55 on the closing ring serves for returning the ring againstaction of the spring. If left-hand cutting is to be done the sprmg andthe cap 53 are positioned at the opposite side of the abutment 50 andthe plug 54 is moved to the lower position in Figure 5.

The spring 51 acts directly in a circumferential direction instead of onthe chaserholders as in some prior constructions. lln such riorconstructions the springs act on the c aser-holders and their actionresults in some of the chaser-holders having trunnion play and othersnot. In actual practice this is of course very detrimental to successfuloperation of the head, particularly in do-' In addition to themeans forrendering the chasers operative and inoperative, as just described, thefront unit of the head is provided with means whereby the diameter ofthe opening between the cutting edges of the chasers can be varied thuschanging the size of the work that can be threaded. Such means comprisesa series of worm teeth at 56 on the exterior of the head body engaged bya worm 57 on a bolt or shaft 58 journaled in the ring 33. The bolt isprovided at one end with a head 59 underneath which is a flange 60having graduations shown in Figure 1 coacting with zero marks on thering 33 to indicate the extent of adjustment. The zero marks on the ring34 coact with indications on the rear unit of the head to indicate thediameter of the opening between th chasers for either right or left handcutting. For adjusting the head the bolt 58 is turned, and this rotatesthe head body and the plate 34 by means of the worm gearing. The rings31 and 33 are held against rotation by pins 47 on the stationary shank63 and the relative rotation of the parts referred to changes the sizeof the opening between the working edges of the chasers. The extent ofrelative rotation of ring 34 and the shank is indicated by the scaleshown in Figure 1. It will be noted that both sets of indications arevisible to a workman who is adjusting the head and this with theself-locking adjustment feature makes adjustment quick and easy. At itslower end the bolt 58 is provided with a thread for a nut 61 and abovethis is a squared portion receiving a washer 62.

The nut serves to force the washer along the squared portion so as tobring the adjacent faces of the washer andthe flange 60 into frictionalengagement with corresponding faces on the ring and so make a neatturning fit. As will be seen in Figure 6 the squared portion of the boltextends up be yond the face against which the washer 62 rests. Whenlooseness occurs due to wear the washer is forced further along the boltby turning the nut so as to maintain the fit without backlash, the nutlocking itself against the washer. with any special locking arrangementfor the worm as the worm is under friction at all times and will notmove from its correct setting. Tn certain previous constructions wheresimilar worm gearing was used, the worm being formed as a thread on abolt extending into a socket in the adjusting ring, the screw so formedhad to be forced down into This arrangement does away frictional lockingengagement with"the bottom of the socket by means of a locking followerin the shape of a screw plug having threaded engagement with the, upperend of the socket. When the workman after adj usting the head attemptedto lock it in adjusted position by means of said clamping screw the wormwould sometimes turn and thus spoil the adjustment. This is impossiblewith the present arrangement and the adjustment of the head is thereforemade with great ease and certainty.

The rear unit The assembled rear unit comprises a hollow shank 63 havingat its forward end a radial flange 64 with openings 65 in its front faceto accommodate the parts 40, 41 and 42 on the front unit. The rear unithas fixed thereto pins 47 projecting forward and serving to lock theclosing ring at one end of its stroke with the chasers in operativeposition. The flange also has recesses to receive screws 49 forengagement with threaded openings in the adjusting ring of the frontunit to hold the two units together. Springs 66 are located in saidrecesses and bear at one end against the bottom of a recess and at theother end against the under side of the head of a'screw 49. The bore ofthe rear unit is enlarged at 67 to receive the extension 36 on the headbody which extension holds the units in line and strengthens the headagainst lateral strains.

0 pemtz'on In the operation of the device so far described, eitherright-hand or left-hand chaser holders are mounted on the trunnions andsecured thereto by screws 46. The operator brings the chasers intooperative position by graspin the handle 55 and turning the ring 31 thusbringing the bores of the bushings 48 into register with the lockingpins 47 whereupon the springs 66 move the front unit back, the shank ofthe rear unit being held securely by a chuck or the like. The work isnow brought up into engagement with the chasers and the threadingoperation proceeds, it being understood that the head advances but doesnot rotate, while the work does not travel but does rotate though thismay be changed in some instances. When the threading of the work hasproceeded sufficiently far the axial traveling movement of the rear unitof the head is stopped by some convenient means and thereupon furtherrelative rotation of the parts draws the front unit forward away fromthe rear unit against the tension of spring 66 until the pins 47withdraw from the bushings 48 whereupon the ring 81 is moved by itsspring 51 in a direction to move the chasers toward inoperativeposition, the pressure of the spring 51 being reenforced by the reactionof the work against the chasers which, of course, tends to open thehead.

Modifications In Figures 15 and 16 I have shown a modified form of thepin 68 having a reduced end at 69. This pin may be used in a headsubstantially similar to that above described, the closing ring 31-beingprovided with bushings 48 as before, if desired. When the chasers are inoperative position the body of the pin enters the bushings but when thechasers are operative the parts assume the position shown in Figure 16.It may be remarked that the front and rear units have relative axialmovement in one way or the other to release the pins from the closingring and permit the head to open, i. e. the chasers to becomeinoperative.

In the modified form shown in Figures 17 to 19 pins 7 O are shown eachof which has a handle 71 by which it may be turned about its axisthrough an arc of 180. The pins are each provided with a collar 72 whichrests in a depression in the front face of the flange 64 of the rearunit. The pins are each provided with an eccentric end portion formed byreducing the body of the pin at one side for a short distance back fromits end face.

The operation of the device with the modified pins is similar to thatfirst described but this form permits the making of either a single cutor of a rough out followed by a finishing cut. Assuming that the partsare shown in the position for a rough cut the chasers will operate asfirst described. For a second or finishing cut the handles 71 will beturned, e. g. from the position shown in Fig. 18 to that shown in Fig.19 and the cutting operation will be repeated whereupon a small amountof metal will be removed producing a smoother result than with a singleout. The eccentric face 73 of the pin is formed on the arc of a circlecorresponding to the circle of the hole in the bushing with which theface is to engage. In this manner the face of the pin is caused'to fitagainst the inner face of the bushing without line contact. When thedirection of cutting is to be reversed the rough and finishing cuts maybe had by merely reversing the positions of the handles 71.

The modification shown in Figs. 20 to 22 is similar to that firstdescribed. The closing ring 31', however, is provided with a pair ofrecesses 74 separated by a face at 75 of reduced height relatively tothe rear face of the ring 31. The bushings 48 have reduced portions tocorrespond to this face. This form of the invention is desirable wherethe handle 55 of the closing ring is moved toward closing position by acam in that it permits overtravel of the ring 31' and so causes the pins47 to take a position in the shallow intermediate part of the recesses.When the handle 55 now is released by the cam the ring 31 is moved backby spring 51 and pins 47 assume their positions in the bores of thebushings 48. In the absence of an overtravel arrangement the positiveaction of the cam might result in injury to some of the parts. In-themodification shown a closing cam can be set without close relation tothe closed position of ring 31'.

In the form of the invention shown in Figare 23 the head which mayotherwise be similar to that of Fig. 1 is provided with an internal tripcoacting with the work 76 for movingthe front unit axially withreference to the rear unit to release pins 47 from the bushings 48 inthe ring 31 and thus permit the closing ring to rotate and move thechasers into inoperative position, the trip mechanism comprising a head77 having recesses 78 for clearance for .chasers when cutting shortthreads and a circular flange 79 at the rear end fitting in the bore ofthe head body 30. A stem 80 extends rear'wardly into the bore of theshank 63. The bore is threaded at its rear end to receive a screw plug81 by means of which the position of the head 77 may be varied to varythe length of the thread formed on the work 76.

Uhasers and chaser holders Figures 27, 28 and 31 show details of thechaser and chaser holder used in this die head. In the chaser holdershown in Figure 27 the trunnion 82 is made integral with the body 43 ofthe holder. In the forms partially shown in Figures 10 and 23 thetrunnion is detachably secured to the body of the holder. The holder isprovided with a recess formed by the intersection of an inclined face100 and a back surface 101, in which recess a chaser 83 is mounted andheld in position by means of a clamp 86. The clamp has longitudinal fins87 and 90, the former inclinedat an angle about'60 to correspond to anundercut face 99 at the back of the chaser. The intersection of theplanes of the faces 87 and 88 is rounded off to correspond with a grooveat the bottom of faces 89 and 99 on the chaser 83. When in position theface 88 on the clamp is spaced a short distance from the face 89 on thechaser. The face 90 is inclined at an angle about 45 and the ridge ofthe clamp is squared at 91, the ridge also having another inclined edgeat 92. The chaser holder has a groove formed at the intersection offaces 102 and 95, the groove being squared at the bottom to provide aspace between the edge of the fin and the block to take care of dirtwhich might otherwise accumulate between the face 90 on the clamp andthe face 102 on the holder. A face 94 on the clamp is arranged to lieflat against face 95 on the holder. The clamp is held to the block bymeans of screws 96 and the chaser may be adjusted longitudinally of theholder by means of a screw plug 97. Although the chaser 83 is somewhatsimilar to chasers heretofore used it differs from them in that thesurfaces 85 and 98 alone are accurately finished. The clearance betweenthe face 89 on the chaser and the face 85 on the clamp allows forinaccuracies in the other surfaces of the chaser, and the clamp.

In Figures 25, 26, 29 and 30 are shown modifications of the chaser andchaser holder shown in Figures 2 and 27. The chaser 83 has facesl05 and108 which correspond to faces 85 and 98 on the chaser 83 but the face106 extends over the entire thickness of the chaser instead of beingformed in two parts 99 and 107, as in Figure 31. 'The back 108 extendsin a single plane over the entire width of the chaser instead of beingin two parallel planes 98 and 89, as in Figure 31. This chaser can befinished much more readily than that shown in Figure 31. The clamp 86,shown in Figures 29 and 32 has a face 104 which extends out over the top106 of the I chaser. A rib 103 extends in acorresponding groove in theholder block. In this form the face 103 is inclined at approximately 45and face 104: at approximately 75.

In further explanation it may be stated that the position of the nuts 40makes it very easy to adjust the trunnions when the front and rear unitsare separated, as Well as to ass mble the front unit or take it apart.In previous construction the nuts or adjusting screws for holding thetrunnions and determining their fioat were inside the bores of 'the headbody; i. e. forward of the rear face of said body and hard to get at.Even when flush with said face they were more difiicult to manipulatethan in the present device.

The use of a single axial locking screw on the trunnion does away withany tendency to tilt the adjusting nut in looking the adjusting nut inplace. In some previous constructions, where three or more lockingscrews were used unequal tightening of the locking screws tended tocause misalinement of the adjusting screws.

By means of the new construction I avoid the use of a separate frontholding ring on the head body. It is a matter of great difficulty tomachine the front and rear faces of a separate rin such as that shown at30 in the patent to llIiller 1,296,546 so accurate-1y that the rear facewill lie closely against the faces in the annular depressions on ring 15and head body A (which surfaces must also be machined accurately) whilethe front face of the ring lies in the plane of the front faces of ring15 and head body A. In practice the expense of such exact machining isprohibitive, and the recess in the head body is cut deeper thannecessary, after which annular shims are used to fill the space betweenthe holding ring and the head body, when it frequently happens that theholding ring is caused to project forward too far.

The inner and outer peripheral surfaces of the holding ring must also bemachined accurately so as not to leave cracks in which dirt mayaccumulate whereby also the smoothness of the front face of the head maybe impaired as by reason of metal chips catching in such cracks. Suchchips also often catch in the slots of the exposed screw-heads andinterfere with the opening and closing of the head. The holding ring hasdepressed seats for the screws which seats often break down more or lessand render the holding action uncertain. Also the screw-heads oftenbecome bent and interfere with the headopening and closing movements.These difficulties are avoided in my present device where the frontholding ring is integral with the head body and the shims, if any, arepositioned between the head body and the rear ring of the front unit ofthe head body and can be of substantial width instead of being of nogreater width than the holding ring of the prior construction, thusbeing made more permanent and more effective. The prior construction inwhich the rear holding ring of the head body is integral and the frontholding ring is removable made a die head which was very difficult totake apart, it being practically impossible to pry the ring out orotherwise remove it from its seat with tools. With the presentconstruction the units can readily be separated. Plate 34 of the frontunit can readily be removed-by taking out screws 37, removing nuts 40,and taking out bolt 58. The entire front unit will then come apart.

The two unit head is a matter of convenience also in the factory in thatthe front unit can be used Without alteration with either a plain rearunit or with a rear unit including a trip mechanism as shown in Figure23. The same details can also be used with a head of the Lanco type asshown in my copending application No. 59,563, filed September 30, 1925.This makes it possible to fill orders for either plain heads or headswith trips with a smaller number of actual parts held in the stockroom.

Another feature of advantage in the present construction resides in thefact that the bores for the trunnions pass straight through the headbody. In prior constructions they commonly are counterbored either fromone or both ends of the head body and the bores must be finished fromone or both ends, this necessitating a much greater number of operationsthan in the present construction and giving a less accurate result ascompared with the resent construction where all the finishing is eitheron the walls of the straight bores or on the flat outer contacting facesat the rear of the head body and at the front of th rear plate 34.

By my present construction the scale on the periphery of the head is inplain view while the bolt 58 is being operated to adjust the head, as isalso the scale on flange 60, which conduces to quick adjustment.

It sometimes happens after a head has been in use for several years thatthe gear teeth 56 on a segment of the head body become worn so thatthere is some backlash between the body 30 and the worm 57 In such casesit is of advantage to separate the front and rear units, remove thescrews 37 and plate 34, adjusting the head body around and then replaceplate 34.- to bring one of the other holes in register with the pin 38.Then the ring 34 has now again been secured to the front unit the zeromarks are brought into the same position as before relative to thegraduations on the flange 64, and a new set of teeth takes the wear inadjusting the head.

It will be obvious to those skilled in the art that various changes maybe made in my device without departing from the spirit of the inventionand therefore I do not limit myself to what is shown in the drawings anddescribed in the specification but only as indicated in the appendedclaims.

Having thus fully described my said invention, what I claim as new anddesire to secure by Letters Patent, is:

1. In a die head, a'front unit including a body having longitudinalcylindrical bores of uniform diameter, trunnions in said bores saidtrunnions having reduced rearward extensions, a plate at the rear of theunit having openings for said extensions, means for holding thetrunnions in place relatively to said plate, and chaser-holders on thefront ends of said trunnions, substantially as set forth.

2. In a die head, a front unit including a body having longitudinalcylindrical bores of uniform diameter, trunnions in said bores saidtrunnions having reduced rearward extensions, a plate at the rear of theunit having openings for said extensions, means for holding thetrunnions in place relatively to said plate, chaser-holders on the frontends of said trunnions, a separate rear unit having recesses in linewith said trunnions, and resilient means holding said units together,substantially as set forth.

3. In a die head, an assembled front unit having a head body withparallel bores of uniform diameter, an integral annular flange at itsforward end, a closing ring and an ad justing ring on said body, a plateat the rear end of the body, chaser-supporting trunnions in said boresheld in place by said plate, an assembled rear unit resiliently held inengagement with the front unit, and pins fixed to said rear unitslidably mounted in the adjusting ring said pins engaging the closingring to lock it in one position, substantially as set forth.

4. In a two-unit die head, an assembled .extension, trunnions in boresin the head body bearing at their rear ends against said rearmost ring,threaded extensions on the trunnlons projecting through holes in saidring, nuts on said extensions bearing against the rear face of saidring, and tangential 139 chasers supported on said trunnions,substantially as set forth.

5. In a two-unit die head, an assembled front unit comprising a headbody, rings about said body, a rearward extension on said unit thereal-most ring fitting about said extension, trunnions in bores in thehead body bearing at their rear ends against said rearmost ring,threaded extensions on the trunnions projecting through holes in saidring, nuts on said extensions bearing against the rear face of saidring, tangential chaserholders on said trunnions, and locking screwplugsin said nuts bearing against the rear ends of said extensions,substantially as set forth. l

6. In a two-unit die head, an assembled front unit comprising a headbody, rings about said body, a rearward extension on said unit therearmost ring fitting about said extension, trunnions in bores in thehead body hearing at their rear ends against said rearmost ring,threaded extensions on the trunnions projecting through holes in saidring, nuts on said extensions bearing against the rear face of saidring, tangential chaserholders on said trunnions, and locking screwplugsin said nuts having tapered front ends engaging in tapered holes in saidthreaded extensions, substantially as set forth.

7. In a die head, a front unit comprising a head body having trunnionbearings, trunnions in said bearings, chaser-holders on said trunnions,tangential chasers on said holders, a closing ring about the bodyconnected to said chaser-holders, an adjusting ring about the body, aring about a reduced extension of said body, means for securing saidring to said body, means for securing the trunnions to the last-namedring to prevent axial movement of the trunnions, a separate rear unit,pins on the rear unit slidably mounted in said adjusting ring andadapted to engage recesses in said closing rin and means for holdingsaid units yieldafily in contact with each other, substantially as setforth.

8. In a die head, a front unit comprising a body member having parallelaxial bores therethrough, trunnions mounted in said bores, chaserholders mounted on the trunnions, tangential chasers in the holders, aclosing ring'mounted on said body and connected to said chaser holders,an adjusting ring mounted on said body, means for adjusting said ringsaround said body to vary the cutting size of said die head, a peripheralflange at the front of said body and a circular plate secured to therear of said body for holding said rings in axial position on the body,said plate being connected to and securing the trunnions against axialmovement of said body, and a separate rear unit having means thereon forlocking the said closing ring in operative position, substantially asset forth,

9. In a die head, a front unit comprising a body member having parallelbores therethrough, trunnions mounted in the bores,

chaser holders mounted on the trunnions,

rear of said member by which the rings are held against axial movementrelative to the said body, the said plate being connected .to andpositioning said trunnions against axial movement in said body, and aseparate rear unit including a shank, pins fixed thereon extendingthrough said plate and the said adj usting ring of the front unit andadapted to engage sockets in the closing ring for locking said ring inoperative position, substantially as set forth.

, 10. In a die head, a front'unit comprising a head body having parallelaxial bores therethrough, trunnions mounted in the bores, chaser holdersmounted on the trunnions, tangential chasers in the holders, a closingring mounted on said body and connected to said chaser holders, anadjusting ring mounted on said body, said rings being held against axialmovement on said body by a peripheral flange on the front of the bodyand a circular plate secured to the rear of the holding the trunnionsagainst axial movement of said body, a separate rear unit comprising ashank, pins fixed thereon extending through the said plate and throughthe adjusting ring of the front unit and adapted to engage bores in theclosing ring on the front unit for locking the head in operativeposition, said front unit and said rear unit having relative axialmovement for releasing said locking means, and resilient means foropposing such movement, substantially as set forth. I

11. In a die head, a front unit comprising a body member having parallelaxial bores therethrough, trunnions mounted "in the bores, chaserholders mounted on the trunnions, tangential chasers in the holders, aclosing ring mounted on said body connected to the chaser holders, anadjusting ring mounted on said body, said rings being held against axialmovement relative to said body by a periphe'ralflange on the front ofsaid body and a plate secured to the rear of said body, the. said platealso being connected to and securing the trunnions against axial:movement in said body, a separate rear unit including a shank, pinsfixed thereon adapted to extend through the said plate and the saidadjusting ring on the front unit into bores in a closing ring on thefront unit for looking said die head in operative position, and means onthe rear unit for locking the chasers in operative position for either aroughing cut or a finishing cut, substantially as set forth.

12. In a die head, a removable front unitcomprising a body, ringsencircling said body, tangential chasers mounted in holders,

m holders mounted on trunnions, the body having parallel axial bores ofuniform diameter throughout, trunnions mounted in the bores in saidbody, said trunnions extending throughout the length of said body andhaving reduced portions extending through a plate on the rear of thebody, and having nuts on the reduced portions by means of which thetrunnions are held against axial movement substantially as set forth.

13. In a die head, an assembled front unit comprising a body member,rings encircling said body, a ring or plate at the rear of said bodycooperating With a peripheral flange at the front of said body to holdsaid rings 5 against axial movement, bores of uniform diameter extendingthroughout the length of said body, trunnions mounted in said bores andextending throughout the length of said body, tangential chasers on thetrunnions, the

said trunnions having reduced ends extending through the said plate andbeing held against axial movement in the body by the said plate on therear of the body, substantially as set forth.

:5 14. In a die head the combination of a front unit comprising a fronthead body member, chaser-holders pivotally supported thereon, tangentialchasers on the holders, a closing ring connected to the chaser-holders,

an adjusting ring, a ring coacting with a flange on the head body forholding the closing and adjusting rings in place, and means for securingthe last-named ring to the front head body member, a separate rear unitcomprising a rear head body member, means thereon for locking theclosing ring in head closin position, and means for securing the headbody members together, substantially as set forth.

15. In a die head, a front unit comprising a head body member having anintegral annular flange at its forward end, chaserholders', a closingring surrounding the body member, a ring adjustably secured to the body,a zero platevcoacting with said flange to hold the rings in place,graduations on the periphery of said plate, and means securing the zeroplate in place on said body member in a plurality of angularly relatedpositions,

00 substantially as set forth.-

I 16. In a die head, a head body, chaserholders thereon, a ring frameabout the body including an adjusting ring, a closing ring, axiallymovable rings, pins on said axially B5 movable rings for locking theclosing ring in head closing position said pins sliding in bearings onsaid adjusting ring, a Worm journaled on the adjusting ring, Worm-teethon the body engaged by said Worm, a head on the worm bearing against aface on the ring, a Washer at the other end of the Worm bearing againsta face on said ring said Washer having a square opening fitting a squarepart of said worm, and a nut on a threaded end portion of the worm,substantially as set forth.

In Witness whereof, I have hereunto set my hand at l/Vaynesboro,Pennsylvania, this 31st day of October, A. D. nineteen hundred andtwenty-five.

HARRY T. SHEARER.

